Portion of a shoe midsole



FIG. 1 is a left side elevational view of a portion of a shoe midsole showing a new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a rear elevational view thereof; and,

FIG. 4 is a top plan view thereof.

The broken line showing of a shoe upper and shoe sole in the Figures is environmental and forms no part of the claimed design. 

The ornamental design for the portion of a shoe midsole, as shown and described. 